1. Field of the Invention
The present invention provides a method for sampling motion of portions of a patient such as portions of the heart which have different movement characteristics and, more specifically, the method is directed toward using magnetic resonance imaging with variable separation tagging.
2. Description of the Prior Art
The advantageous use of magnetic resonance imaging wherein a patient or object is placed within a magnetic field with alternating generation of RF pulses and gradient pulses serving to excite nuclei within the area of interest and cause responsive emission of magnetic energy which is picked up by a receiver and may be processed by computer means followed by recording, display or production of hard copy of the results has long been known. See, generally, Atalar-McVeigh U.S. Pat. No. 5,512,825 and Conturo-Robinson U.S. Pat. No. 5,281,914, both of which are assigned to the owner of the present invention, the disclosures of which is expressly incorporated herein by reference.
It has been known to employ two sets of tagging planes oriented orthogonal to the image plane in imaging two dimensional heart wall motion with magnetic resonance imaging through spatial modulation of magnetization (SPAMM) approaches. See U.S. Pat. Nos. 5,111,820 and 5,217,016.
U.S. Pat. No. 5,275,163 discloses the use of magnetic resonance imaging and monitoring motion of a part of an object. Pulse and gradient sequences are applied in pairs with spatially differing tagging patterns with subtraction being employed to form a tagged image.
U.S. Pat. No. 5,352,979 discloses observing a phase angle response of volume elements in a slice or volume and imaging occurring before and during perturbations caused by external stimuli.
U.S. Pat. No. 5,379,766 discloses quantitative motion evaluation of a portion of an object by employing a high contrast tagging grid for detection of tagging patterns.
U.S. Pat. Nos. 5,315,248 and 5,545,993 disclose tracking of motion.
In spite of the foregoing contributions to the art, there remains a need for a method of providing high resolution images of myocardial motion wherein portions of the myocardium being imaged may have different movement characteristics.